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Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 23)
Time and Work
23.
A and B can do a piece of work in 30 days, while B and C can do the same work in 24 days and C and A in 20 days. They all work together for 10 days when B and C leave. How many days more will A take to finish the work?
18 days
24 days
30 days
36 days
Answer: Option
Explanation:

2(A + B + C)'s 1 day's work = ( 1 + 1 + 1 ) = 15 = 1 .
30 24 20 120 8

Therefore, (A + B + C)'s 1 day's work = 1 = 1 .
2 x 8 16

Work done by A, B, C in 10 days = 10 = 5 .
16 8

Remaining work = ( 1 - 5 ) = 3 .
8 8

A's 1 day's work = ( 1 - 1 ) = 1 .
16 24 48

Now, 1 work is done by A in 1 day.
48

So, 3 work will be done by A in ( 48 x 3 ) = 18 days.
8 8

Discussion:
61 comments Page 4 of 7.
Kamal said:   9 years ago
How 2 comes in the first step?

I can't get it. Explain me clearly.
Lavanya said:   9 years ago
I am not understanding how they work 10 days?

Please explain it.
Sajal said:   10 years ago
I want to ask that why we have solved the equations at the top?
KEYA said:   4 years ago
(A+B+C) = 1/16.
(B+C) = 1/24.

Hence,
A = 1/16 - 1/24 = 1/48.
(16)
Hanumant said:   1 decade ago
I am not understanding how to calculate 1/48.7/240.1/80?
Dharmendra kushwaha said:   9 years ago
@Suji.

Your explanation clears my doubt, Thank you.
Sikandar said:   1 decade ago
As 1 day work = (A+B+C)-(B+C).

= 1/16-1/24 = 1/48.
(1)
Gurjit said:   1 decade ago
why subtract 1/16-1/24 on the above equation a=1/30
Ramkumar said:   1 decade ago
Ramkumar:.

Good question but easy to understand.
Gautham Raj said:   9 years ago
I can't understand this, please someone help me.
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